Liquid level indicating, recording, and controlling apparatus



2,672, l 55 PARATUS March 1954 J. M. CALDWELL LIQUID LEVEL INDICATING,RECORDING, AND CONTROLLING AP 2 Sheets-$heet 1 Filed May 21, 1946 T m. uw 1 :-'INVENTOR 0554-7 4/0470 (bl 0022 L Patented Mar. 16, 1954 LIQUIDLEVEL INDIC AND CON TROLL ATIN G, RECORDING, IN G APPARATUS Joseph M.Caldwell, Arlington, Va. Application May 21, 1946, Serial No. 671,379

11 Claims. (01. 137-412) This invention relates to an improved apparatusfor indicating, recording and controlling the level of liquids and moreparticularly to an electrically actuated float suspension devicedesigned to indicate, record, and control the fluctuation of the levelof the surface of a body of liquid with a high degree of accuracy over awide range of variation.

Heretofore apparatus used to indicate the level of liquids generallyhave been designed around a mechanical float member linked by directmechanical means to level indicating, controlling and recording means.This linkage arrangement relies solely upon the motion of the float inresponse to the movement of the level of the surface of the liquid toactuate the mechanism and its fluctuations vary directly with thebuoyancy of the float and its relation to the liquid level. The powerneeded to operate the device and to overcome the inherent friction in amechanism of this type has made it necessary to use extremely largefloats'thereby sacrificing the obvious advantages gained by the use of afloat unit of smaller horizontal cross-section. The conventional typefloat unit with direct reading indication has been found unsatisfactoryfor measurements wherein extreme accuracy is imperative. Moreover,theselarger float units cannot be used in installations where the spaceis restricted because of surrounding structure or where the quantity ofwater available to move the float is very limited. 1 V

An object of the inventionis to overcome the disadvantages enumeratedabove and to provide a simple and inexpensive device which will enableliquid levels to be indicated, recorded or controlled with a high degreeof accuracy.

Another object of the invention is to provide a liquid level indicating,recording and controlling device which will enable a float of relativelysmall horizontal cross section to be used without sacrificing accuracy.

A further object of the invention is to provide a float actuated liquidlevel indicating, controlling .and recording device which does not relyon the force from the float being out of equilibrium to move thesupporting member and members connected with the indicating, recordingand controlling means.

A still further object of the invention is to provide a float actuatedliquid level indicating, controlling and recording device which may haveits float unit located some distance from the indicating, recording andcontrolling means and at the same time not sacrifice accuracy.

An additional object resides in the provision of an improved method forindicating changes in the surface level of a body of liquid and forrecording such changes and in controlling the factors involved in suchchanges when desired.

The arrangement of the device is such that the float itself is used onlyto give an indication that the liquid level has changed and to give thedirection of that change. The connections to an electric motivatingmeans are such that once the float has indicated a change in level, itwill determine the degree of change in liquid level by moving the floatassembly either in an upward direction or in a downward direction inproportion to the change in liquid level to maintain the float assemblyat a substantially constant position relative to the surface of theliquid. By combining an indicator, a recorder or a control valve of thedesired design with the float suspension member, the level of the liquidmay be very accurately indicated, recorded or controlled. The powerwhich moves the suspension member and the indicating, recording andcontrolling means is furnished by an electric motor and not by thebuoyancy of the float as is the case in most conventional apparatus ofthis type.

One application of the invention is to indicate and record the liquidlevel in small-scale hydraulic model studies, wherein the amount ofwater to actuate the float is small and the changes in the levels are ofrelatively small magnitude.

Further objects and advantages of the invention will be apparent fromthe following description taken in conjunction with the drawings,wherein:

Fig. l is a diagrammatic elevational view of a liquid level indicatingdevice illustrative of the invention with liquid level recording andcontrolling means shown operatively included therein;

Fig. 2 is a diagrammatic elevational View of a modified form of theapparatus shown in Fig. 1; and

Fig. 3 is a sectional view showing a modified form of float responsiveto changes in the level of the liquid surface.

With continued reference to the drawings and more particularly to Fig.1, the apparatus is illustrated in a functioning position in a containerHi. The float ll, resting in liquid I2 is attached by shaft l3 to rockerarm Hi. The rocker arm is constructed of a stiff, dielectric materialand is pivoted to turn freely on and about pin l5 which is fixed intothe foot assembly IS. The foot assembly is also made of dielectricmaterial and is secured upon the threaded end of shaft l1 and heldrigidly fixed thereto by pin l8. Shaft I'I constitutes a support for thefloat assembly and the elements associated therewith. The actualmovement of rocker arm l4 around pin I5 is restrained to a smallmagnitude by contact screws l9 and which are firmly screwed into thefoot assembly l6 as shown. The contact screws are lockedinto position bylock nuts 2!. Whenthefloatll. and rockerarm M are in a state of stableequilibrium while floating freely in the liquid there is a slightclearance between contact screw i9 and contact plate 22 on the rockerarm and between screw -2ildandzcontact plate 23 also on the rocker arm.Aslight rise in the liquid level will raise the elevationrof the floatand the rocker arm thereby bringing contact plate 23 into contactwithcontact screw 20.

This contact between the plate and the screw closes an electricalcircuit through electrical source 24 andelectricalrelay 25. The excitingof relay 25: closes a circuit through contact points 2B;"21",.28 and'ZQ,electrical source'til and the armature I of motor 3| mounted onstationary lplatforni'32." The field of motor 3| is excited constantlyb-y electrical source 33;' thus the closing o'f .thearmature circuit bythe action ofrelay 'i25causes the. motor shaft 3 3 .to rotate. The..movement of the motor shaft rotates the mechanical wormifwhich isfixed to the motor shaft 34 .,-by keyi3|i.*"The worm 35 coacts withwormwheel {.131 thereby transmitting its motion to the said wheel. Thecenter portion of worm wheel 31 is '.threaded on shaft Il.

(Shaft-J I1. is prevented from rotating with the worm .wh'eelby staffrod 38 which passes through a hole.in platform 32 and is fixed to. theupper .-.cross.member offoot assembly It by pin 39 and touthetopasse'mblyltfi by pin M. Top assembly .40. is. flxedlto thev shaft ITby being. screwed .Zthereon andlpinned. thereto by.pin.42. Worm i;wheel. 3.! isprevented from movingin an upward 1. direction on the shaftllby clamp43 and bearing. .Washer 144.. Clamp 43- is in turn fixed .to

platform 32bybolt 45. prevented from moving in a. downward direction onthe shaft by sleeve 46 and bearing washer 44. ..-As a-.result.ofthenabove-described restraint of 1.-shaft. l1 and wormwheel 31,. therotation of the aworm wheel-forces the shaft to'move either .upwardly ordownwardly depending on the direction of rotation of the worm wheel. Thewiring 0f-.-motor 3| is so. arranged. that when relay 25 is.closed theshaft. H is raised by the. rotation. of

the motor shaft 34. The rising of shaft turn raisesrthe foot assembly.as and causes the (contact. screw-20 to-separate from contactplate 23.This separation of the screw and plate breaks uthe'circuitto relay 25which inturn breaks .the circuit to the armature of motor 3| therebybringing the motor .to a halt and. stoppingthe rise of-shaft |I.

If the liquid level falls from the equilibrium tpositiomthe rocker armwill move in a clockwise .1.direction until contact screw -|9isibroughtiin contact with contact plate 22. This action closes relay41. and thereby contact points48,,49,. 50, and 5| :which in turn closethe circuit to the arma- .tureofmotor 3 I. The direction of current tothe armature, however, is reversed from that ex- --perienced by theclosing ofwrelay 25; thus the direction of rotation of the motor andworm wheel is also reversed andthe shaft ll isforceddown- .wardly. Thisdownward movement of. shaft inturn causes the rocker arm 14 torotate-ina Worm wheel 31 also in turn starts the motor in such a way as torestore the relative position of the liquid level, the floatl|,,";the'-r'ocker arm l4, and the shaft l1 to" their equilibriumposition, and maintain the afloat assembly at a substantially constantposition relative to the surface of the liquid.

' Since-staif-rod-38 is fixed to shaft l1 by pins i39.and4:| andassemblies l6 and 49, the vertical movement of the staff rod reflectswith a very high degree. of accuracy. the movements. of. the leveliofjliquid |2.., By engraving. a scale onto staff 1tod33 andbringing itintoindex with. a

reference mark oruvernier m fixed .toplatform 32 by support...53 andbolt 54 the rise and. fall of the liquid. level. withreference to theplatform 32 is indicated by readingthe vernier. By attaching a pen armassembly..55 ,tolthe staff rod 38 and bringing thepenfifi against a 1conventional clock-drivenrecording drum 5l;sup-

ported on table.58.fixedtolplatformi32 by pin 59, the rise and fallofltheliquid level is recorded on achart 6t mountedon the. drum,.thereby making a permanent record of the. fluctuations of the liquidlevel with time.

Through the .use of a commercial type. valveifil the supply of liquid.flowing into container'l 0 may be replenished thereby controlling thelevel. of such liquid with a high degree of accuracy. The valve ismounted on platform 32 andfixed'thereto bypin.62. Theopeningandclosingof the valve is accomplished by. movement of the ,valve hand1e63reflected from the motion of staff rod 38. The valve handle isattachedthereto by sliding. pin. When the liquid has reached the'de-.sired level .thevalve will be in a closed; position and willremainthere until the floatassemblyl6 has .moved in adownward direction.

y connecting. .the float I .to, the rocker ram 14. at a point between.the pin l5 and the contact point23 the motion .of the float is.amplifiedtat the contact point and produces a betterbreaking andmakingof the electrical contact.

Fig. 2 is an. application of the invention wherea in a chain oranalogous flexible member'65 is used in-lieu of, the. threaded shaft,being secured at its lower end tothe assembly l6. Inthis application theifloat unit and electrical connections are precisely as described above'incconnection with Fig. l, and. hence the-connections aremot.fully-shown.

- form l: and. has a pulley Wh6161-fiXedtO the motor shaft overwhich'the chain or analogous flexible-.member .55 passes, to a second: pulleywheelifillh The-weight of the float: unit assembly .46 is supported bypulley. wheelsfi'l; 68 and is balanced by acounterweight ;-69 secured tothe end of the flexible member. The. rise and fall of the level of theliquid-|2, is indicated -.on the scale .10.. (supported; on platforms).by, movementof the pointer 1| which is adjustably..fastenedto..the.,chain65 by. set screw-I2. vThrough the use. of this vapplication. of. .the. invention the float unitmay. be located,..quitea.,.distanc.e from the indicating means without curacy. A recording drum51, control valve 6! as described in Fig. 1 may also be desired.

Although change in the level of the liquid may be reflected by the floatll mounted on shaft 3 to rocker arm I 4, the same results may beaccomplished by the use'of a free moving float unit as shown in Fig. 3.

In this modification the float 13 is confined in an open ended hollowfloat chamber assembly 14 which is partly immersed in the liquid 50 asto allow the float to move in upward or downward directions only. Thuswhen the level of the liquid l2 changes the float will move, bringinginto contact screw 75 and contact point 16 or pin 17 and contact point18 depending upon the direction of the movement of the surface of theliquid. The closing of the electrical circuit by this contact activatesthe motor in the same manner as was described in connection with Fig. 1,thereby causing the foot assembly 19 supporting said hollow floatchamber to rise or fall until equilibrium has been reached, at whichtime the contact will be broken. The contact screw 15 may be veryaccurately set with the desired clearance and locked in position by locknut 8%. Contact pin 71 is likewise set in position and there locked bymeans of a set screw 8|.

It can be seen that the described embodiments of the invention willindicate and record the liquid level constantly within the limit ofclearance set between the contact screws and their respective contactplates. As this clearance can be set to very small values the error inthe indication of the liquid level will at all times be very slight.This feature is not found in the usual type of float operated indicatorfor they usually rely on the float to drive the indicating and recordingmembers. This results in a tendency for the float to move by jumps forthe static friction of the various guides and the recording pen restrainthe float, until there has been a considerable displacement from theequilibrium position when it suddenly moves to its new equilibriumposition. In an attempt to overcome this feature, the floats aresometimes made very large in order to provide additional force toovercome the static friction in the guides and the recording pen. Suchlarge floats are often undesirable as they take up considerable spaceand require quite a quantity of water to displace them. Theseundesirable features are eliminated in my invention as the float doesnot operate the recording pen and move the guide rods. The float I I isof sufficient size only to move the rocker arm [4 and thereby make theappropriate electrical contact. The motor 3! does the remainder of theWork of lifting or lowering the shafts, guide rods, recording pen andcontrolling valve.

It will be obvious to those skilled in the art that various changes maybe made in the embodiments of the invention without departing from thespirit and scope of the invention and therefore the invention is notlimited by that which is shown in the drawings and described in thespecification but only as indicated in the appended claims.

What is claimed is:

1. Apparatus responsive to changes in the level of the upper surface ofa body of liquid, comprising a movable support, electromotive meansoperatively connected with said support to raise sacrificing acvernier52 or a connection with mounted on platform 66 if I and lower it, across member securedto the lower trol said electromotive means in amanner to cause said float and said movable support to follow changes inthe level of said liquid.

2. Apparatus for indicating the position of the control saidelectromotive means in a manner to maintain said float at asubstantially constant position relative to the upper surface of saidfluid, and fluid level indicating means operatively associated with saidsupport.

3. Apparatus responsive to changes in the level of the upper surface ofa body of liquid, comprising a vertically movable support, electromotivemeans operatively connected with said support to impart a verticalmovement thereto, a pair of carried by said support and adjustablerelative thereto, electromotive means controlled by said contacts andoperatively connected to said movable support to impart vertisurface ofsaid liquid, and means including electrical means operatively connectedbetween said adjustable contacts and said electromotive means changes inthe level of said liquid.

4. Apparatus for indicating and recording the position of the upper freesurface liquid in a reservoir and for maintaining a predevoir, arecorder mounted on said support, a pen attached to said rod andcooperating with said recorder for recording the liquid level in saidreservoir, means for supplying liquid to said body of liquid, a valve insaid supply means, and a t omega control lever on; 1 said a. valve:operably connected tosaid. rod for maintaining :the levelof liquid insaidreservoir: substantially constant.

5., Apparatus for; indicatingrand recording the position of the upper:freev surface of a body of liquid .in a reservoir andmaintaining apredetermined level comprising a stationary support mounted above saidbodyofliquid, an elongated member mountedzfor .vertical movementrelative to said support, poweroperated means mounted on said supportand operative toraise and lower said member, afloatiassembly mounted onthe lower end OfxSBid member and Jadapted-tobe partially immersed insaid liquidpsaid floatassembly comprising a pair of adjustable contactsand a rocker arm pivotedintermediate its length between said contacts,said rocker arm having a pair of contacts and a float associatedtherewith for operating said contactsqnand' controlling said.power-operatedmeans to maintainsaid assembly at a substantially.constant position relative to i said surface of the liquid, asubstantially vertical rod connected to said member and: movabletherewith, graduated scale markings-'onsaid rod, vernier attached tosaidsupport and cooperating with said scale to indicate the liquid levelin said reservoir, a recorder mounted on saidsupport, a pen attached tosaid rod and cooperating with said recorder for recording the liquidlevel in said reservoir, means fortsupplyi-ng liquid to said body ofliquid, a valve in said supply means, and

a control lever on said valve operably connected to said rod formaintaining the level of liquid in said reservoir substantiallyconstant.

, 6'. Apparatus forz indicating and recording the position of the upperfree surface of a-body oflliquid in a" reservoir and maintaining apredetermined level comprising a stationarysupport mounted above said:body of liquid, anelongated member mountedfortvertical movementrelativeto said support-,-*power-operated means mounted on said supportandoperativetdraise and lower said member, a floatassemblyxmounted onthe "lower end of saidnmembenand adapted tozbe partially immersed in:said liquid, means included in said float'assembly for controlling saidpower operatedimeans to maintain' said assembly :at a substantiallyrconstant position relative to said surface of the liquid, asubstantially vertical rod connected to said member and movabletherewith,

graduated scale markingson saidrod, avernier attached to said support 1and cooperating with said scale to indicatewthe liquid level insaid-reservoir, a recorder mounted on said support, a pen 2 attached tosaid rod and cooperating with said recorder for recording theliquidlevel in said reservoir, means for supplying liquid to said body. ofliquid, a valve in said supplymeans, and a control lever on said valveoperably: connected to 1 i said rod for maintaining the level of liquidin said reservoir substantially constant.

'7. Apparatus for indicating the position of' the upper free surface ofa body 10ft liquidnin a reservoir and maintaining a predetermined levelcomprising a stationary support mounted above i said body of liquid, anelongated member mounted for vertical movement relative to said support,power-operated means mountedon said support and operative to raiseandlower-saidmember, a

float assembly mounted on the lower end of said member and adapted to bepartiallyimmersed in =saidliquid; meansi-ncluded in said iloat' assemblyfor controlling saidpowermperated means to maintain said assembly at asubstantially constant position relative to saidsurface of the liquid,

a substantially vertical rod=conneeted-to said member and movabletherewith; graduated scale markings on said rod, a: vernier attached tosaid support 4 and cooperating with saidscale to indicate the liquidlevel in said reservoir, means for supplying liquid to sai'dbody-ofliquid, a valve in said supply means, and a control lever onsaidvalve operably connected to said rod for maintaining-thelevel of liquidin said reservoir-substantially constant. 8. Apparatus for indicatingtheposition of the upper free surface'of a body of liquid :in areservoir and maintaining apredeterminedlevel comprising a stationarysupport mounted above I said body of liquid; an elongatedmember mountedfor vertical movementrelative to said support,:=power-operatedmeans-mounted on said support and operative to raise and'lower saidmember, a fioat assembly mounted on thelower end of said member andadapted to be partially immersed in said-liquid, means includedinsaidfloat assembly for controlling-said power-operated means to maintainsaid assembly-at a substantially constant position relative to saidsurface of the liquid, a substantially verticalrod connected-t0 saidmember and movable therewith,

means for supplying liquid to said-body of-liquid,

, port to impart a vertical movement theretogan open end hollow--membersecured to the lower end of said support, a float-insaid hollowmember having a limited vertical movement relative thereto, a pair 'ofvertically spacedadjustable contacts in said hollow membena contacton-said float disposed between said adjustable contacts and movable intocontact with one or the other of said adjustable supports as the liquidlevel rises or falls, and means including relay switchesoperativelyconnected between said adjustable contactsand saidelectromotivemeans to control said electromotive means in a manner tocause said float-and saidsupport to follow changes in the level ofsaidliquid.

10. Apparatus responsive to changes inthe level of the upper surface ofa body of liquid, comprising an elongated flexible member, meanssupporting saidflexible member intermediate its length, electromotivemeans drivingly connected to said I supporting means to impartlinealmovement to ,saidflexible member, a float assembly comprising a-movablefloat anda pairofspaced electrical contacts operated alternatively bysaid heat secured to one end of said flexible memberand adjustablerelative thereto, a counter-weightsecured to the opposite end ofsaid-flexible member, and means interconnecting said contacts and saidelectromotive means to control-said electromotive means i in amanner tocause said floatandflex'ible member tofollow changes intheleve-l' oftheupper suriace of said body of liquid.

11a Apparatus responsive to changes in the level of the upper surface ofa body of liq-uid, comprising a vertically movable support,electromotive meansoperatively connected with said support to raise andlower it,'a cross member secured 'to the lower --end-of said support,adjustable spaced apart'contact'screws carried by said cross members andinsulated therefrom, a-rockevarm pivotally supported intermediate itslength between said adjustable contact screws, contact plates on saidarm, a float secured to said arm operative to tilt said arm to move saidplates into contact with their respective companion adjustable contactscrews as the level of said liquid rises or falls, said float beingpositioned on said rocker arm in such a manner as to amplify the floatinduced movement in the making and breaking of said contact, and meansto control said electromotive means in a manner to cause said float andsaid movable support to follow changes in the level of said liquid.

JOSEPH M. CALDWELL.

References Cited in the file of this patent UNITED STATES PATENTS NumberNumber Number Name Date Reiber Mar. 27, 1923 Steiner Dec. 18, 1928Moffett Apr. 10, 1934 Ryder Oct. 1, 1935 Manley Oct. 6, 1936 SchmidtJune 4, 1940 Wagner Feb. 5, 1946 Hicks Sept. 2, 1947 Buss et a1. Aug.29, 1950 FOREIGN PATENTS Country Date Great Britain Apr. 26, 1934

